HR: 11:35h
AN: P32B-02 INVITED    [Abstracts]
TI: Oxidants on Small Icy Bodies and Snowball Earth
AU: * Yung, Y L
EM: yly@gps.caltech.edu
AF: Caltech, 2100 E California Blvd, Pasadena, CA 91125, United States
AU: Liang, M
EM: mcl@gps.caltech.edu
AF: Caltech, 2100 E California Blvd, Pasadena, CA 91125, United States
AU: Liang, M
EM: mcl@gps.caltech.edu
AF: RCEC Academia Sinica, P. O. Box 1-48, Nankang, Taipei, 00000, Taiwan
AB: Oxidants such as O2, O3, H2O2 and SO4 are known to be on the surface of icy bodies in the outer solar system and they may be an important source of energy for the subterranean biosphere. During Proterozoic time, Earth experienced "Snowball Earth" events, associated with the nearly complete shutdown of the hydrological cycle. During such long and severe glacial intervals, a weak hydrological cycle coupled with photochemical reactions involving water vapor would give rise to the sustained production of hydrogen peroxide. The photochemical production of hydrogen peroxide has been proposed previously as the primary mechanism for oxidizing the surface of Mars. During a Snowball, hydrogen peroxide could be stored in the ice; it would then be released directly into the ocean and the atmosphere upon melting and could mediate global oxidation events in the aftermath of the Snowball, such as that found in the geological record. There are implications for the evolution of oxygen-mediating and utilizing enzymes and thereby paved the way for the eventual appearance of oxygenic photosynthesis.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0325 Evolution of the atmosphere (1610, 8125)
DE: 0330 Geochemical cycles (1030)
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
DE: 6223 Callisto
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting